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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4c73f83a195500427178f52e8e103663dfc04a25978e9f419ed8464f23f26e2' 
  AND token = '71CiH3BrqYpqrbiykTPpE2hxFoRkfnyKvdxo7IGunw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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