SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a21339dca22a70bc30bf57b7255071f3535c16e07ef4034498f87218e4f8366' 
  AND token = 'C9TDUC5yUreQJvvYA5F0NdrKNDc8oX0wkJa/l6iIxoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}