SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8274e5ce2e217a232578ed23df6d173b276b63ac872c49eba2691fa11845d6ca' 
  AND token = 'mvedXqFwqVCBA/J6TZkd+MGOWNtOOQ0aOei6bxhCVGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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