SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50a133198f5173a48ad1bfa74f554bfb688f404a691ceba689ddae8f7d3cea65' 
  AND token = '+cOVFh+gwSJb6cAfu2+WkBaG8Mwdg8LmvQKLLHluAuI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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