SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9599a386d24777156c1526aa8eb45c67df2dc1282f65dd414500bec4666d481b' 
  AND token = 'l+niWbVpXseqqxQitkxDJYMM530Lxi+q1ZwEtBIbH2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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