SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d47752325325849764c10fec7633c1953bbaf83c4f6a61a7ce2a1295a08e2af' 
  AND token = 'JzsY5mBO5zXwP3Mn/1wLVG/j3Tt+pyotCYyKjk5ZQkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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