SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cd37af2a3dd29c3cb7f97ec0ccc0038f5324403cab6387dbf77f00854a8cdbc' 
  AND token = 'x/ppZJ53cvGqn+VdHgY1Vgxa1FioYGzqIKPoRwazRUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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