SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0760f8ff566dfd768d750510a7a9cf13585b48b9c498f94afb7f2055e9d51f3' 
  AND token = '2H9XMN2hZB2oI5yvNmKQjeb7ETMnWvfTzjfn9xRBCDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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