SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18a1c6790f26b9060e264adbec483c9ddd75b497bafb698602835f87641dfba6' 
  AND token = 'gaw8dagh9UaXNhmSUV08hDgFfCWEjlKTmQ35BcWXVXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00112

JSON explain

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