SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5416f7582d736c0a3ee7ce4b4c313ca2adcf2cc1365cadd9bc2bed12e57ce249' 
  AND token = '6HpyaNxjEOWNYaL9+ObtLoOqQpaJDVcZ/NcJyQtTOrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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