SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6b83cf557e5717a812e50ef85d5d1c9f9e3a1cb7945fd08548e92753d75f31ee' 
  AND token = 'eh600BGIb1tzeSx+iImsUuW3ox29nHPu2MZWEDrXfqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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