SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b605bec3f562e37e2f9e083f24776b78aa08d72b3b65d83a95cd12ae6888bf92' 
  AND token = '6ghoMZackcB0wNFhPoTdkvbUIwDMIiKUNTuR+4kWQi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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