SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78b4d759b5d29d49a3e5302dbdc6639e72bee0c81da48e1c671ffb7ba4a2523b' 
  AND token = 'YTeMMbZ2A1V28KvYJDJc13UW846TeN4B6cauQYB6o/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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