SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68754a335d05bfb6cda34f26ccbeb8e786d92e4e044c7da48312bf7ebe1fda8b' 
  AND token = 'W3WzlVXG/zdrlOxLkVT/fYgwviELBUJe/k4gR/8CHDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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