SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '42acf35b89dbf5aab06def27d34e883a4287d274c68bb40f7474d6ea5a69f3b8' 
  AND token = 'nkAZ00VZ2HAmBKHRtD4Vgv8/q3EG5hBWZToEVvXV/4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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