SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db0b6e2bb78213982b7d78701c69942b67ecd35026330a0faf4a71ffc2ed5742' 
  AND token = 'gkrHVfpc/wh6FrjV+yFTEMlJAQtpjVADK805BMn2JqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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