SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e20e041b2c295982b4579faab4d6b9fa85cf4e524352e1576a6860828ee2666' 
  AND token = '61lESP9xPcnjuqVMZ8EvBUAMDsUxYNKjZJcvmq/LGzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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