SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '520478553074873621cede7a7dbf38045ff4433a5e51a353631a3dee8ce45ffb' 
  AND token = 'ZX0H/UXNdedb0tl4NlEuKM5EipTWDZw3qzXDrjHUT2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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