SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '116fc8b17d148cdfead1028c3e89a89915209f5bc30d701603415abc64c5a52d' 
  AND token = 'lPmmr0o5krUubWBmEasX0RBPpdAxoN4pSZrMsoRYsnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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