SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3a4fe687b7b48070e64ca59b551c533dc452fcfe8d2e41e430d76faf80b4264' 
  AND token = 'JwkH7eiM80Z/hyfJ9YqevwGf+WKhZqcfMg6FOaZmtn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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