SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9d5c8f46d5724996c12a8ca0c455a86448e964abea40a5f8bc6c4238c7d97da' 
  AND token = 'RHsoobvAOd8nswJnT9dyMk4aRVn1CVBXm1g7je1f1eY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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