SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '853a53a99add8cb9d68f03f878be3948f31dd1fd1762412c98619186328a0af7' 
  AND token = 'xDIjEPK8HOi7ozOQs3rzbiC/FUMOP/Gt125ilfNcDR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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