SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4eca09374471a5a42b0d4087cc037fba3a24bce81425f741ac2e3a7a6bbc9bf' 
  AND token = 't4RnhLNc1uVLrd2zhHDJyN/tJO6llWcUbbb4u1GPVY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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