SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7654c20478334e066447db8024f5b223dd446183b2b50c74fe7d2bf5d271f255' 
  AND token = 'd3TloSfHYHmKXJwnIi2PIZQVOc9jbbavgrZI64+rRDY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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