SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c20e16b314b5afd8522e4a5aae2fe753c02cb6708569052d85aaece742ed5d4' 
  AND token = 'EqVD82sQpLDqAaNSJO8HwnySLR+UEY476BDmdb2abAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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