SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '7446b2e369bd2d1abbecef0f255123e39848715ae0469efec0d3dbdac537de0d' 
  AND token = 'f6VEz1HxKFrl2uRBKLOmPt+211XpgUSK36WduwCjxTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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