SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '608435057dcbcc4f1f9e2019e9fb2b5ae20f82dbf80d67d3d74cdabe3448adfc' 
  AND token = 'ljquIuOivrsQ5heuUmNVxa1dpLGBjXBESLYX9GgP/N0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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