SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b84b0866d36c191d85dfd461374a5e6980122a1c784231424cd333e33d1ff04d' 
  AND token = 'fnezTM9fBO+iNnesXZsn9aSfDs4VbamH74kRrrKeIaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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