SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4abbeca71a7c85192b29df6f4edba12c9ac066823168025c6b8c16a90b8a41e9' 
  AND token = '6DHQtqj4m2gHGEzHjuEbiBDVLvJBlmfn1f3Cvej36Zg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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