SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94c1c6f46f34b95fd1a8f6c2ee1af588dd12915de2d5568b216f141d26171d21' 
  AND token = 'zbO3G5nouPNOwE6AyYN/JGs/HoCxsWYVb87NprraqbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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