SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd673f842799f06e699995e07c0c2244761b6d5a24c3683615d61d0fc1563266' 
  AND token = 'RnpRLZBIZWJedsGXcQLYcI9wP+pDVt9+zlhYwLm7Fv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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