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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b5ab5b1408ef7e4a73cbbce750f861c35155532eb6d1f5ade84aefdb637bda8' 
  AND token = 'LUCwkFX9qXk3ypnXhlBuP1pg4NWlkoAQUtzKLqWIA1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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