SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38852743ee3318b920e60f2e74ca8974f29a035113a600bea56593ecdf57c275' 
  AND token = '/50bULDNgPjkqGHNLiNPWjTpVv1/vlxwgA6Qtcib+MA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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