SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c2291b2b0939d8dddaf289de5ed021b982e024cbed990591eb0d14b3736e0d2' 
  AND token = 'BGpDUqwH+6gGj9IcubKyqJsCkXrGYHUAAhdQMjOvWxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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