SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dea3f271e1fbc8d7d72744c67eed9cb25128df39d1f3375f68329e1e2809a1b4' 
  AND token = '96p9sCkBDjY+rBS2nZKrEsCS6rKWAYf0mDwyJ51Sc2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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