SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '268ac6942c4310aa46c9310134012efcb569e88e31749145b3d6fad12f1a52e7' 
  AND token = 'o+PDjRclKsOAR/psnCXZxrxHznXzQZi3IaEhns0YvKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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