SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74beb4d89f8d3240f91eee523748f1c46ac16e5d813031eea71d921402eebc51' 
  AND token = 'Hwt+xzUSMmStyYMiD33YwiCLc3Pwc91A4NpA/iNznWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}