SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa77dc5316e852057ebfa2334db0a3b52bcdc8d12ca0cf776082644d56d0202d' 
  AND token = 'Yb79nYgQ/z/Bx5qkbLxWyO4iHAGVKBmFBWoLRrjZywk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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