SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88553fed95a9df023d4b6fcfb717a0a60326937ab04243de246096abaed92d57' 
  AND token = 'Ls3qdxxpryZo68i4e1SZgyn1ryiYmuiwfKDFCNUaLPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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