SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0728e165825edc09f5826e54804deef9cd47d1f01d6bece0aa615b7f973e74c' 
  AND token = 'xPzzyTaYRrceFXtdBZdhtReVuACJy3I6+1g14RhvtZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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