SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dde937738092afafbee333ec1ce32fa8ccec4ae07c12606eea44fcf2fec4f85' 
  AND token = 'KCxQwxXvvHArxma+TZsh9JOFUxjYNU2CKlhuK3nTvoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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