SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42817d610062f2d538723cd1f3e0047e49e8c8ee93a437c7763af195c76d2a0e' 
  AND token = 'oSz+LLetm1Nq6eU5CE1ZtVlOGcLus1RMvrHTACPCjwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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