SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71348bd6765551cda1aa4cd746acea30e7bb8382a79c36920d98f09533e3172a' 
  AND token = 'RK6L0khQ5Q4kB6PwOQthHMjcrM2fhNal2i+EXZUZkC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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