SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0f46c97b9809f26489095a0d12b2c50be3b0528fe6a86e872df7edb5bcee862' 
  AND token = 'eLEJsLR73CphQqABGdh7zbEGpUplMl1a4d0L+PGLmXM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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