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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fff029169856f4b4dd12374ebaabf841f2513bbdc1badf8df51cf0ffab504ec' 
  AND token = '5h0qRoQJJAOUdDbaX9emVx2PErpBIj2+b4whcB19WWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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