SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a80f1fed9af7f932846960200701f76eb646dfd3e026f564a23bcaedad11650' 
  AND token = '+r2mrgWIFF6DOGKWIi6S1QHwQ8bORJXKGSPVaHtb89Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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