SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39f8d69f7874bdc1e5a92f3e289f7b31d276c85bc329afd4fd7a26e399af3d83' 
  AND token = 'BIQmG0qxox7XVRl+NCrG6ZWsrL3NBz46whQON6cqaF4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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