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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d8e8b327c9721dc5c532d02c0d1481f8f384a1bc02ed35f0172c853e99b1cde' 
  AND token = 'XXfkkmtwHVxnZOJ3ukBnMUWd/NoOWKOZzKpdRS+f2tQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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