SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14956b3279e34a58f3f9941f0ed16401a9afff4dba2e9ca29f3defa4c8980d82' 
  AND token = 'n+NkkEDIPa57/Ty8ZQHOwY26ByFhGUZz0o/ul6mk4bk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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