SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5519b0f6d37ad8629d6f0bd7f75488b1747e0b92d283813ed1f5b4952704900b' 
  AND token = 'lSLIk+WhGOdYF1qv5rNk+ClC+XYmLPohjyZGCt/zKTE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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