SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b3bac443790d78c0ccce92e77bfe7502c3967421cf058941f7a9a6ba7f45e23' 
  AND token = '+DA1GGaS/2hUgV+xvi9buQqwRMUf9kZoWtwKUAshxHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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