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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dbaa7e59c340a152fc0010dd03cf35722f8f4dbf4c1ff8460b9a06df3f541b2' 
  AND token = 'YkAc/FjiCKd8PiZ3Jy6mdF4u+6/QEncy8ORKMYK4HFs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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