SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '938dc0ccd3d8accaa553f26bf91fd624aedbec1aa4a5c95bfd6ee66777fa503d' 
  AND token = 'D7kvPj/TuXFhTmrEXET17RRlaUDueS8N/KQUBJp7RKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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