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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7f9ce3ffd2daf18062dec40c8d0f3e0645b6abe704c98fb2ca3b23e73879827' 
  AND token = 'JLLyUku2tcWzq1dD2qyvlFQ57EJ7v2M+VjKrsHWJE6w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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