SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd75826cd9bf7bd789a1a3003b32d35a878e6d7b508f991896d5027e5b21c0eac' 
  AND token = 'la7i2/zWYYznk6fk56dlW2BIgeuSeXWfHXseMR4YPYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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