SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3091beb8f810134643b9d82a8565925e0c9c2a459e41a3b4db323afef499d45' 
  AND token = 'ghCj6cRX4HOJgh9SxMDb37wt2tuE7w5mGfmfgxDd9rI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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