SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '057eae8359550b07deab4615957d01520473e560e34d68596bf38b8cedf79c30' 
  AND token = 'imS1kvtIQRAIwu71FqTeIW1+I/GNjB91hIYZg+yZr5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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