SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a4ab976122188c583f08fc8f651f79eaf101875806b7576a403908ff678b620a' 
  AND token = 'CIxNzJetwwZB11Ap25GdxVssIW+Ukag9xNgUHFnbo50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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