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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8de4fc5f6deed2fb524a70cae891de32ad3684ca1ab4f8e775533bdbb853c23d' 
  AND token = 'x/q5ZHTfAkcQFGy4b7jBOvt/ghpxrLcOf3KX7tdMAjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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