SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d90b37720c2b728787338976f15513364aa0fdfccf5441f4adc839f156a1c3a' 
  AND token = 'EwgwxqWT1w3SV5mzMOv9iAiqixpd8ndXZRvOsUCGKTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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