SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad98f56e4f51a4bd522a619fc50a12380c869746f078264436bb75f040639b67' 
  AND token = 'e19YALShCGRVjl2Gved5pbOfv+vd9cbanktuCM8LgLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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