SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '2876553a90bdc6a300ef0d7cd1ad564640827049fc53416f2942aed53df8148a' 
  AND token = '53Spj2+k+Ob95uzExtWobhbwgAdAMrooapEWOq3PV3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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