SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76de75e73b8f964367cf58ec966d1611705c390b2d0205861e20e84fea44f6a1' 
  AND token = 'bIakP95THakhKVUzsOXHrpVDX4LnXGbh++nKOfAkong=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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