SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '977af322339252e8340ab547aa382341a3b8173e69df155aa88da656d6d49ae2' 
  AND token = 'GUCJB7rQq0u2NngGu0f1D/d7NsGVuTzMNbSyxfbGADQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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