SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71fb4ff206ef01ca639b57a028248fb84fe97c4f32662fb47c2c12f8cdc7f6fd' 
  AND token = 'MBMsWvJdEFx9FgNnvNkJrnO5kGMO2phCXg/+roQLHjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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