SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a18ac3f42f517321ffa899b55da0cb0f2943857171ea0818635db1fd0783a04b' 
  AND token = 'r2Zt2lVvCfE/KQHVMAhytd5vYNtg5t6crpZD2+vbcfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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