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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b784869a8b5425a332834b5d705999d82a30e22c36a21c0cc427ad3029e79d53' 
  AND token = '81V7Ss0pFHh+huU8ziVuVapw7DeezqPHkeMrvzYha3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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