SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc93eb84d9c5f6281cf5c6a94d7d4091471ae5d843f1e51b7c6783455793cb39' 
  AND token = 'N2d1e//WwRV9kAuUFnKhTs+ld7ybNLzBRtjlnvUE6Fo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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