SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8042ffe22145ecdd2261a96f3a9985f9be846550a6cc5478b9beb53fc04893aa' 
  AND token = '5jkh+5MsLVD/ar5XyA7Fzo95v6i1iOvUDpLjTV3dUb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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