SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '842b5b3beff7470ce1029936184e6e6eb942dfdc02de5f0dc2687c5874842d6f' 
  AND token = 'jcpWoAMUFwro5fYADSg1s37f6u4Phjn5C7bmY7Plzr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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