SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '32eb88ed28c36efe6a1b1580ab913778b266f062bde2c7fee97ccda899c83395' 
  AND token = 'BCMcxkuA3Eh9lLodwu/pc9HAqApVx8fnMmZNFf/PAxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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