SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4e726db14ba2e25efd62ac35b43e8fb2f9b9eac71369683563091004f04bd12' 
  AND token = 'ApUkgj/W9IDfCAmvL5vVYlhgGcwuQxRqHRTOB672dQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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