SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '276f4e96aa4ad666661607115da59fec1af24315c8275e2998e47f49be441bd6' 
  AND token = 'Wa/hIYHRrWjszOCdyY9ToyJWCDhtV2KGgamzovs4NPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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