SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a12089f5d58323d3be13e0983a6c6e8467cb4257da975829bc17c450ebbbaa70' 
  AND token = 'FJryvgF7jBx8OxAlTxv5UZJDoi1xshr+BoHWK0xyIac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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