SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '686ddf8f9dcf6c31ff6d5d7c3a5540884b2e43a4113159313c204897dddc3ad1' 
  AND token = '4yyKg0jEmQ8miy10nnbepVB6JRv4V765UwBaDxm4gvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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