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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3265f834f4a33854b609f39125832f5de0d90174996a9be0a04ea103d1228389' 
  AND token = '7xV1v+XrldXBxgt8Xsrr8lzxOpAEK1oouvl5YClxomI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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