SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6b4087d520aed24b4131d1b960610e51ee2c1c9a9f1175045fc288900ef2835e' 
  AND token = 'IgJ8JBu1nCfiRdl9p1+e9WBx+KRynUtBhoPppjZ8hmk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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