SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6df91b9a87345589f941255f0ff4d012aab2c7b407af0831223fbf029c21368c' 
  AND token = 'yAEZPpIJ6RZgLpj4sPcQYLFvKdffKCUI2LfcgqMmq60=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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