SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42a1514d2b5a723afc4744e452545301d2636496e5e1731c8d46077b47bbfd6c' 
  AND token = 'pKKcoQejaTqF3C87TqiQcUNJd2PVOVPBh1cvc3/iTkc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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