SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '336135d8153d5858820bd4ac6d6ef49971a22549fec67c756a38d9a93bcfb896' 
  AND token = 'Uj1H9VVcpbdPkh/eI5mIkwAND2+SKCzFpQ25gonkvz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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