SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78b31d16ff2f7c255ebc946350cbaee8c1c4dc420dd42dcaadefe81cfc3dca5f' 
  AND token = 'U8NkbPPQifiE6Tp00J57FS9HOEj1TnDc2nTDYivsLKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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