SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3eea62193be0fd51f664a17661ae17b372db7d7d3e6675478c8eaeb5e9073591' 
  AND token = '8uDMqvkVVHnclxYmt5xIhiB6+PjR394PwPU2VoSgoyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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