SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '156bc3dee144621fbe31fd8592832e0c4fd68cc9e38bb10a75a5dcd8bfaf77ae' 
  AND token = 'AGMhpnRawZkTABnV5tUBuYWO1Qq0/STaDBK91Sf+hKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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