SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c0dc1b0c85220482a219da98ee61c53143fbbd6e9ed95e923472461ad610aa39' 
  AND token = 'fkX/V944ww8HtVLEBlODnYEZdvELEkQKEZROfYW5F9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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