SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83bab37d0d54e0131a6bc579ada6788d39c0152060c75be2beb9bfe04b3fdc2f' 
  AND token = '+fE7ZXSTwiOj80nnl26Btz0Q3nMiM8MMbKURoby7o4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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