SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fdf02125a2f36951540237e333e0e2e79698265688dacb99532dbbd4e0df819' 
  AND token = 'JhD/No058GMLHUnWP31nKYuP6WnPwS0xlQJfKZJBcR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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