SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b51d161b494f223118e67d5db464f411eb575b5e923bd86c5105796ebc41615' 
  AND token = 'bKXzKkTWjUb5Xy2mKsGwiKETz8+hxmNKwVhhp7LMupY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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