SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4632b0433683181de84313e25721756c11635b65e946a6b008e1a5ef017294fc' 
  AND token = 'UZO+1CoOhApuQzVUDiQWmXjW3P8p+VmxDt15+1mn+1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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