SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4eee77011f08815326dc6018c3bacd2f94b6522dbbd64e22dc52a20f6d62f44' 
  AND token = 'z+5BjYaJUNmUuQTGsSScreKgZ8AAnM2/6TxDqU+MhjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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