SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a9ffd4afedd317006c295455480515c3589947588dd66ea8a74d6e0f9d0e378' 
  AND token = 'MsyJ6jQNTiGwDKNMYHDtUhqSgU4PbSJel3Xsg09PEDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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