SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a10a5b4a4b58cdc365fd7ee2b3cd8d405e133741209bbcdcf1606e502274f267' 
  AND token = '68SrkAS6nt/ZBTBaI2GuSc9wxzrcpy2eK9kBXmlrDb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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