SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70fc5abb344d3ee8173537b0339bdda2c20ba34817b68b85f7d7411313bfad14' 
  AND token = '5PCx2TgDNTKjQnIYwRAGtYmqgOcVRJwkAOGD+lxnKH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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