SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45ddd4c3e8178e2587af512ce059e9cbdb15d67a07dc7b0ac924fb313d92cc2e' 
  AND token = 'F2paGo5b/tBMVH4a2Y3MPO1ltgCeA8jpOFj7B2UUJs8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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