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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8189b2fffd70d9a74421c27b74116185ceb4506df1ff54c2cfaaeaa4d58a5e36' 
  AND token = 'cK2vkoxkJs7pYwEEZ1SaxQRB2lvTpLbUYJLUnZxG1Uc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}