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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b957b8ee39b0fc5fd4a4b9aebbcfe3dd6ceb9d3c72820eb3cd98b3558cbde939' 
  AND token = 'pseE9fLzNJLlzjf7qZo4Rx+MVAsfvHRNxG7pdp53wYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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