SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68572b60d0812ba84847410ead21e07852102e97f66eb238a9fe8dc12161d2dc' 
  AND token = 'T8t8wkOQ8rM5kB9enRAjmwiJ2JBvsLk+7Evw9pVXQrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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