SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f391e8857c5cd0634c3558c34a4278d2f8118eb4ac7d000ebbf9bf02fde030a6' 
  AND token = 'ciRz6T/xdRt+eXHIgJ3JpmuQAtqwePN+eCPJYtHAom4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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