SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6b7da2561d0d446c6d6b6e185ece4113d3f928c4d15952eeb05210332dd86dc' 
  AND token = 'QMvwk+LYZBwj1oVIsiTqUG62qWQgzO693chvjS/63q8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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