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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df1cf951406f5e9b43546aa50a7e9b9e1249120372d1e80e14d35ce0a4ba7097' 
  AND token = 'pVjmOi0NHL5c6NmUyZyOz0NVRIYZfmuzQV8aLiYIj3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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