SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55c53baae8f18f1e5c6fc662ff11fddd663f866cfa6eeae069fbe7903c1da501' 
  AND token = '3UffiJDEiu1XM3bVJps0vN8xkKc0KXZHHkQInXpnmX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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