SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88f4db7b7c405171fa5926dbea2fd04de535bfff56af28934ac35ff9836e4a40' 
  AND token = 'eQbdGqAlnbQNhw4/3s54FiZGsky7eHa2VpCNhYpV1d4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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