SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5e7bc6c1e9f20b5d555fa7204d1eecbca48990b3f38eb0fb195feee6cc119fe' 
  AND token = 'O6udAJ1hSwQA5v7+ahtcVvdKjU9seqsYoWb6ULWWmC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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