SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40b3a4c6aa66d9d11bcecea3aee39300b3df410c159ec1191ef50e4045632ef8' 
  AND token = 'rV8upNEUKJBLyPFuoE5dhRzi6AKLeWDgbts5uYGlV04=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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