SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8983e5a648501a2ea560ce0f25e50f6cd04bd96190499e99b7cae429c35300e1' 
  AND token = 'k+SCXsumLCYvupRfDLQ5KhlRwPmtWnSkc2y0mbIsooE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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