SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd78f4851bcf54807d3d39c9a32ebedad830e7a1b7979dff7f043940292ed0727' 
  AND token = '8gqNxXkYGLGSUU5D4wAt2EUVmYTmIgGkz8DgoFNrEh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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