SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8c0409526a639efc096260cd8548f36c4370663d67675520633b486b6675cc5' 
  AND token = 'pAzhTeCJdW+qC17j4I6f4SZ5kbbS/DBkZ6/fei2kSYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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