SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77e91835e6e52284624375c75ef92cc10587975b27823296a4eb547487d0afec' 
  AND token = 'Cv/uf+mdZzJRI9DFVYq0GGEwBJOT9sIbO/eRp0bf6dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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