SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3449305df4780953bb1b694fdd9f39ef63878b588e0b3e27273dde9157cdb90a' 
  AND token = 'wYzM5PZiq3+k0btEHyprtBNUW9dc6FkMiQkwnITfbvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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