SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad756f7da01bf41621c48f675874bd58417b0ebe9d25dd5dc06293bc32f1befa' 
  AND token = 'WPFviYcNGvET4RFHu33InojCK5JhMwEUSZh236yU73U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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