SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0afdbe7c6728590ee32196c995bd92092ba1b3b714a3eeb04da03e56f0545cf' 
  AND token = 'FcPJJv/808AhL2U7ZiumYZkdIU177XRBhQFU6KzJkfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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