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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5d519d812ca1b9be9b0600f8260bcb4d7b261c914309eb4cc98ac81997b3a9c' 
  AND token = '2D0NzoLzT0Yfw/6eZHtgYVbsk/HiVCWyaRqYLOM1cYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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