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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de9971a9098e1cc9d0d8ad5b7606d6a8f5834a86d3828af29081e912897a820f' 
  AND token = 'dScwJB2Gaeh6Aw4DQ/MVR5sIWKhGC8+ewzc5LfCKb9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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