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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37da18b062fe6fbd5f259271746427b46a15c961299b754852387ec55958237f' 
  AND token = 'QixyPY7dS91yRKyOj5nDzhSTJwMjpHN+EjlTX67YfK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}