SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b177b2f0f0168028110ef2fb0af5a00bf337b136fde2a33d20fd202ec0f49689' 
  AND token = 'eNtvijhhCN48vJ5xdp/Po+UMAz1HbSDofKQJV7xfuD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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