SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b8ce0692182008decfc054b47d6ba0cf4c42a7d4ec24af8b8bcf0438b19b877' 
  AND token = 'OHwE9Cq42swm6QiHXHOuutNynW5/IAQsWSSVGY5xPm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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