SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '492fad7bf4aadb329fe60a6911142848869e30b982af0d2c250ec38b746dd81b' 
  AND token = 'xSXpXlvnSMXeEpfU/2KlXrsxfHRf1hEAnEhh8ZI0ZdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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