SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e50e87d4c15af67f6f1d73f0659563b583fb6b77739f0410dddeecf4e464781c' 
  AND token = 'ar+b2HDdYaNoRUQYS92BzRTuAtY45zFJsZmWUIxHlPE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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