SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a47d7fba50ade5072886bdb92050fab80d9cfc3a233ac2f716faba90cb7d3984' 
  AND token = 'jGGwd3UszGenhJvOjeguHRPcF8Y3wzeFFU8n6D+niZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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