SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3377eb800abc9894853a6c77fca17dfa4d8be352d143f83d65df69e9a7b78649' 
  AND token = 'umKhh/4u+Wo5cq4WI6pgBldvCHoynzsRvSSz8998qb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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