SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756e9d993111ec39f9a0daf92a2ccb012f6333a046581eb261b793fbeb5acf6f' 
  AND token = 'kNXSgIZXP5audLywS7Fw4A+km38qKexeliZxomJyN5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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