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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc2c6c72ab5c6fe34a3ba1b30edd76c62f9bc4c8961e56e8266fae0686ade6cb' 
  AND token = 'Vk2OgfIcKmDW1+Qz7M6ewoBCD0EgGaKIZziJu/tp0T8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}