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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3669ccb61dfbd252500f1ecaa7ed467397f4f7e6f9da5cbc4cfc48c85a46365' 
  AND token = 'O9KJr+f7u5It3jl7XZJJj2Pu/2BeR+osfp3z1YQuJuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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