SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3776977c3727069306d02cf9b160c9ab9aebeb74ddade28faef316427195471f' 
  AND token = 'vJ6kZhHXNmm8RGMPxd78PCVLIm8jBEuCGWrxV4OEGGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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